Aasco flywheel is here.

[thstone]

I am having a LWFW (and new clutch) installed right now. Should be done by tomorrow.

After reading through this thread (and others), there is no way that removing the DMFW and installing a LWFW can cause crankshaft failure. No how, no way. All production engines are factory balanced to the degree necessary (along with the proper design considerations such as bearing placement and type) to ensure proper and sufficient engine balance.

No engine is in perfect balance, no matter how much time and effort you put into it. Some engines can be in better balance than others but meeting the engine balance criteria to ensure long-term engine reliability is easily met by standard design and production methods.

Harmonics are a red herring in this discusion. Harmonics have very little energy unless a forcing function is driving at one of the harmonic frequencies. Yes, this can happen to a really old bridge in high winds but can't happen in a modern engine because the only forcing function in an engine is the cylinders firing which create the primary or fudamental frequency.

Beyond that, there's nothing in an engine (analogous to the wind in the bridge example) that would drive a harmonic with sufficient energy to cause catastrophic failure of the engine.

The DMFW is meant to reduce minor engine vibration from being transmitted to the body and interior (as part of NVH control), not to keep the engine from self destructing.

[07Prototype]

What type of clutch are you going with?

[insite]

Originally Posted by thstone

After reading through this thread (and others), there is no way that removing the DMFW and installing a LWFW can cause crankshaft failure. No how, no way. All production engines are factory balanced to the degree necessary (along with the proper design considerations such as bearing placement and type) to ensure proper and sufficient engine balance.

You're assuming the aasco unit is balanced. I had mine done this week. The clutch / fw combo were 17g out of balance. 15g of that was the flywheel. That can break a crankshaft.

07proto - I use a sprung spec stage 1

[thstone]

Originally Posted by insite

You're assuming the aasco unit is balanced. I had mine done this week. The clutch / fw combo were 17g out of balance. 15g of that was the flywheel. That can break a crankshaft.

07proto - I use a sprung spec stage 1

The outer section (approximately 4 pounds (not grams)) of my DWFW was flopping around like a beached whale because the damping material was so worn. That had to create vibrations that were 100x what any LWFW might cause due to out-of-the-box unbalance and its probably been that way for several thousand miles.

Any flywheel that is several grams out of balance won't destroy an engine - or a failing DMFW (with 4 pounds wobbling around on the end of the crankshaft) would be the end of every engine.

I installed a Sachs High Performance Spring Hub Clutch, PN: 88-1861-000-017. Drove it home today, runs and shifts great.

By the way, I skipped replacing the IMS too. If it's gone 90,000 miles, I figure that there is no reason why it won't keep working. Call me an idiot if you'd like, but I'm spending the IMS replacement money on new tires and more track time.

[insite]

How many g's do you think are exerted outward by centripetal force at the edge of a flywheel turning 7300 rpm? 100? 1000?

Try ELEVEN THOUSAND THREE HUNDRED. 11,300g at my redline. That means 17grams becomes 425 lb. Over time, that wobble can absolutely fatigue the crank. It's not forged, it's sintered.

[thstone]

Originally Posted by insite

How many g's do you think are exerted outward by centripetal force at the edge of a flywheel turning 7300 rpm? 100? 1000?

Try ELEVEN THOUSAND THREE HUNDRED. 11,300g at my redline. That means 17grams becomes 425 lb. Over time, that wobble can absolutely fatigue the crank. It's not forged, it's sintered.

My point is that the crank won't fatigue because the force (your calculation of 425 lbs) is far below the fatigue load. This situation isn't like bending a paper clip back and forth until it breaks. This load level is more like me trying to bend a street light post. No matter how long I push on it (months, years, decades), it ain't never gonna break.

This is why owners can drive around with a failing DMFW for thousands of miles (which produces 100x the force of your example LWFW) and everything is still ok.

[insite]

Originally Posted by thstone

My point is that the crank won't fatigue because the force (your calculation of 425 lbs) is far below the fatigue load. This situation isn't like bending a paper clip back and forth until it breaks. This load level is more like me trying to bend a street light post. No matter how long I push on it (months, years, decades), it ain't never gonna break.

This is why owners can drive around with a failing DMFW for thousands of miles (which produces 100x the force of your example LWFW) and everything is still ok.

Sorry, you have no idea what you are talking about

[Cloudsurfer]

Originally Posted by insite

Sorry, you have no idea what you are talking about

Totally Agree.

[thstone]

Originally Posted by insite

Sorry, you have no idea what you are talking about

Ok, I'll agree and maybe I have it all wrong. Can you please enrich my understanding:

If I recall correctly, most metals have a stress below which they can withstand an infinite number of stress cycles (me pushing on a light post). Above this level, the life disminishes in proportion to the stress and number of stress cycles.

So, the question is: How does the load you calculated (425 lbs) compare to the fatigue stress of sintered steel?

[Jake Raby]

What is illustrated here is a lot of imbalance, but it is what we see on a daily basis. For some reason no one wants to listen to our experiences, including the manufacturers of the imbalances components.

What is clear in the experience of insure is the fact that these assemblies require balancing before installation. This something we have known for a decade, but something that no one seems to concur with.

I gave up trying to share, we just apply our experiences to those who seek out our specialized services. Glad to see the engine is smooth now, at least we were effective.

[Iflylow]

Sounds like this one has been goin' for a while, and it's all over but the cryin'.

In aviation, we take harmonics very seriously, and I am constantly amazed at the fatigue which is caused by seemingly unrelated components. As a very graphic demonstration on harmonic resonance, go to youtube and search "helicopter resonance CH-47" (I'm trying to avoid any copyright problems by not posting a link)

If you aren't already convinced of the dangeers, you will be after watching this. If I remember correctly, This was caused by one blade which was out of balance with the rest.

[Cloudsurfer]

Originally Posted by insite

You're assuming the aasco unit is balanced. I had mine done this week. The clutch / fw combo were 17g out of balance. 15g of that was the flywheel. That can break a crankshaft.

07proto - I use a sprung spec stage 1

That's interesting. When I had my AASCO flywheel/ SPEC pressure plate balanced to my crank, the pressure plate was off 2 grams, the flywheel was off 3 grams. That's more in line with the quality standards that I expect from top notch companies like AASCO or SPEC.

[insite]

Originally Posted by Cloudsurfer

That's interesting. When I had my AASCO flywheel/ SPEC pressure plate balanced to my crank, the pressure plate was off 2 grams, the flywheel was off 3 grams. That's more in line with the quality standards that I expect from top notch companies like AASCO or SPEC.

I have the printouts from the machine. I'll post them when I have a minute to scan them. I also took some pics of the fw with the material removed. I could feel / hear it over 4k rpm. The only reason I pulled the tranny was to balance.

Jake had another good point: the knock sensor can pick this up & dial back the timing.

[Cloudsurfer]

Originally Posted by insite

I have the printouts from the machine. I'll post them when I have a minute to scan them. I also took some pics of the fw with the material removed. I could feel / hear it over 4k rpm. The only reason I pulled the tranny was to balance.

Jake had another good point: the knock sensor can pick this up & dial back the timing.

Never said I didn't believe ya Just sharing what my results were when I balanced. It would seem very plausible that the knock sensors could pick up this up if there was enough of it too.